1. Field of the Invention
The present invention relates to the liquid discharge recording head which is used for an ink jet recording apparatus, and the method of manufacture therefor. The invention also relates to the structure of piezoelectric element which is used for the liquid discharge recording head or the like.
2. Related Background Art
In recent years, there has been widely used the printer that adopts an ink jet recording apparatus as a printing device for a personal computer or the like, because of the good printing capability, as well as the easier handling and lower costs thereof, among some other advantages. The ink jet recording apparatus has various types, such as to generate bubbles in ink or some other recording liquid by the application of thermal energy, and discharge liquid droplets by means of pressure waves exerted by such bubbling; to suck and discharge liquid droplets by means of electrostatic power; or to discharge liquid droplets by utilization of pressure waves exerted by an oscillator like a piezoelectric element.
Generally, the one that uses the piezoelectric element is provided with the pressure chamber which is communicated with a recording liquid supply chamber, and the liquid discharge port which is communicated with the pressure chamber. Then, the structure is arranged to provide the pressure chamber with a vibrating plate having piezoelectric element bonded to it. With the structure thus arranged, a designated voltage is applied to each of the piezoelectric elements to allow it to stretch or shrink to generate warping vibrations in order to compress recording liquid in the pressure chamber, hence enabling liquid droplets to be discharged from each of the liquid discharge ports. In recent years, the color ink jet recording apparatus has been in use more widely, and along with this, it has been demanded to enhance the printing performance thereof, such as higher resolution, higher printing speed, and the elongation of recording head in particular. To this end, it has been attempted to materialize the higher resolution and higher printing speed by the provision of a multiple nozzle structure formed by a minutely arranged recording head. To minutely arrange the recording head, the piezoelectric element should be miniaturized for discharging recording liquid. In this respect, an elongated recording head can be manufactured in higher precision at lower costs by arranging the entire process to be completed by one continuous semiconductor film formation process.
However, a method adopted here is such as to form the piezoelectric film of piezoelectric element by burning the powdered PbO, ZrO2, and TiO2 which have been molded in the sheet form. Therefore, it is difficult to form the piezoelectric film in a thickness of less than 10 μm, for example. Thus, the piezoelectric film cannot be processed easily, and makes it difficult to miniaturize the piezoelectric element. Also, the piezoelectric film formed by burning such powder is subjected to being affected by the crystallized granular boundaries which cannot be ignored when the thickness of film is made smaller to make it impossible to obtain excellent piezoelectric characteristics. As a result, there is encountered a problem that the piezoelectric film formed by burning the powder cannot provide sufficient piezoelectric characteristics for discharging recording liquid when it is made thinner than 10 μm. Due to this incapability, it is impossible to materialize a small recording head with the necessary characteristics to discharge recording liquid satisfactorily.
Furthermore, in order to obtain ceramics in high density the dimensional changes due to shrinkage cannot be ignored for the powdered sheet when burning it on the vibration plate, and the structural member of ceramics simultaneously at a temperature of as high as 1,000° C. There is automatically a limit as far as the size is concerned. Here, 20 μm is the limit at present. It is made difficult, therefore, to arrange a plurality of liquid discharge ports (nozzles).
Also, there is proposed in the specification of Japanese Patent Laid-Open Application 11-348285, the structure of an ink jet recording head which is micro-processed by the semiconductor process using sputtering method. The proposed ink jet recording head is characterized in that platinum is orientationally filmed on monocrystal MgO, and then, the perovskite that does not contain Zr layer, and PZT layer are formed thereon to provide a laminated member. Now, as one of the inventors hereof has described precisely on pages 144 to 146 and others in the “Sputtering Technologies” under joint authorship with Kiyotaka Wasa and Shigetomo Hayakawa (published by Kyoritsu Publishing Co., Ltd., on Sep. 20, 1992), it has already been disclosed as an effective method to film PZT or PLZT after having filmed the PbTiO3 or PLT, which does not contain Zr beforehand, but the lattice constant of which is not largely different, for example, or by introducing a step of making gradual increase during processing so as to change the film of PZT to that of PLT in that order. Here, the Zr is eventually educed to a substrate priorly when forming a piezoelectric member that contains Zr like PZT.
Further, the method proposed in the aforesaid specification of the laid-open application has significant problems as given below. (1) By the method of manufacture disclosed in the specification thereof, it is impossible to obtain any mono-orientational crystal or monocrystal PZT which is stabilized with good reproduciability. (2) By the method of manufacture disclosed in the specification thereof, it is impossible to obtain the orientated PZT but only on the monocrystal substrate which is extremely expensive, such as monocrystal MgO, leading to an extremely expensive processing eventually. Then, furthermore, the monocrystal substrate of MgO has a limit in its size to make it impossible to obtain a substrate having a large area. (3) In accordance with the method disclosed in the specification thereof, conjugation takes place on the joint portion of the pressure chamber (liquid chamber) member and the piezoelectric member by use of adhesive agent or in the vicinity of the piezoelectric member to make it extremely difficult to obtain reliability with respect to the repeated stress or the like in the area of micromachining which is accompanied by microprocessing.